Re: [RFC v3 1/3] MdeModulePkg/PciHostBridgeDxe: Add support for address translation

[Laszlo Ersek <lersek@redhat.com>]

Thanks for writing up the details!

Comments:

On 02/23/18 09:53, Heyi Guo wrote:
> PCI address translation is necessary for some non-x86 platforms. On
> such platforms, address value (denoted as "device address" or "address
> in PCI view") set to PCI BAR registers in configuration space might be
> different from the address which is used by CPU to access the
> registers in memory BAR or IO BAR spaces (denoted as "host address" or
> "address in CPU view"). The difference between the two addresses is
> called "Address Translation Offset" or simply "translation", and can
> be represented by "Address Translation Offset" in ACPI QWORD Address
> Space Descriptor (Offset 0x1E). However UEFI and ACPI differs on the
> definitions of QWORD Address Space Descriptor, and we will follow UEFI
> definition on UEFI protocols, such as PCI root bridge IO protocol and
> PCI IO protocol. In UEFI 2.7, "Address Translation Offset" is "Offset
> to apply to the Starting address to convert it to a PCI address". This
> means:
>
> 1. Translation = device address - host address.

OK, this looks like a sensible choice to me. It means that the "apply"
term used in the UEFI spec means "add", which (I think) is the "natural"
interpretation.

> 2. PciRootBridgeIo->Configuration should return CPU view address, as
> well as PciIo->GetBarAttributes.

OK.

>
> Summary of addresses used:
>
> 1. Base and Limit in PCI_ROOT_BRIDGE_APERTURE are device address, for
> it is easy to check whether the address is below 4G or above 4G.

I agree that PciHostBridgeLib instances that do not set a nonzero
Translation need not care about the difference.

(1) Still, can you confirm this is a "natural" choice? Were the
DmaAbove4G, MemAbove4G and PMemAbove4G fields originally introduced with
the device (PCI) view in mind?

... I also meant to raise a concern about the InitializePciHostBridge()
function where we call AddIoSpace() and AddMemoryMappedIoSpace() --
which end up manipulating GCD -- with data from
PCI_ROOT_BRIDGE_APERTURE. I can see you modify those call sites in the
patch, so that's good. (I do have more comments on the actual
implementation.)

>
> 2. Address returned by
> EFI_PCI_HOST_BRIDGE_RESOURCE_ALLOCATION_PROTOCOL::GetProposedResources
> is device address, or else PCI bus driver cannot set correct address
> into PCI BAR registers.
>
> 3. Address returned by PciRootBridgeIo->Configuration is host address
> per UEFI 2.7 definition.
>
> 4. Addresses used in GCD manipulation are host address.
>
> 5. Addresses in ResAllocNode of PCI_ROOT_BRIDGE_INSTANCE are host
> address, for they are allocated from GCD.
>
> 6. Address passed to PciHostBridgeResourceConflict is host address,
> for it comes from ResAllocNode.
>
> Contributed-under: TianoCore Contribution Agreement 1.1
> Signed-off-by: Heyi Guo <heyi.guo@linaro.org>
> Cc: Ruiyu Ni <ruiyu.ni@intel.com>
> Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
> Cc: Star Zeng <star.zeng@intel.com>
> Cc: Eric Dong <eric.dong@intel.com>
> Cc: Laszlo Ersek <lersek@redhat.com>
> Cc: Michael D Kinney <michael.d.kinney@intel.com>
> ---
>  .../Bus/Pci/PciHostBridgeDxe/PciHostBridge.c       |  74 +++++++++++---
>  .../Bus/Pci/PciHostBridgeDxe/PciHostResource.h     |   2 +
>  .../Bus/Pci/PciHostBridgeDxe/PciRootBridgeIo.c     | 112 ++++++++++++++++++---
>  MdeModulePkg/Include/Library/PciHostBridgeLib.h    |   8 ++
>  4 files changed, 167 insertions(+), 29 deletions(-)
>
> diff --git a/MdeModulePkg/Bus/Pci/PciHostBridgeDxe/PciHostBridge.c b/MdeModulePkg/Bus/Pci/PciHostBridgeDxe/PciHostBridge.c
> index 1494848..e8979eb 100644
> --- a/MdeModulePkg/Bus/Pci/PciHostBridgeDxe/PciHostBridge.c
> +++ b/MdeModulePkg/Bus/Pci/PciHostBridgeDxe/PciHostBridge.c
> @@ -32,6 +32,29 @@ EDKII_IOMMU_PROTOCOL        *mIoMmuProtocol;
>  EFI_EVENT                   mIoMmuEvent;
>  VOID                        *mIoMmuRegistration;
>
> +STATIC
> +UINT64
> +GetTranslationByResourceType (
> +  IN  PCI_ROOT_BRIDGE_INSTANCE     *RootBridge,
> +  IN  PCI_RESOURCE_TYPE            ResourceType
> +  )
> +{
> +  switch (ResourceType) {
> +    case TypeIo:
> +      return RootBridge->Io.Translation;
> +    case TypeMem32:
> +      return RootBridge->Mem.Translation;
> +    case TypePMem32:
> +      return RootBridge->PMem.Translation;
> +    case TypeMem64:
> +      return RootBridge->MemAbove4G.Translation;
> +    case TypePMem64:
> +      return RootBridge->PMemAbove4G.Translation;
> +    default:

(2) How about we return zero for TypeBus, explicitly, and then
ASSERT(FALSE) and return zero for "default"?

> +      return 0;
> +  }
> +}
> +
>  /**
>    Ensure the compatibility of an IO space descriptor with the IO aperture.
>
> @@ -411,8 +434,12 @@ InitializePciHostBridge (
>      }
>
>      if (RootBridges[Index].Io.Base <= RootBridges[Index].Io.Limit) {
> +      // Base and Limit in PCI_ROOT_BRIDGE_APERTURE are device address.
> +      // According to UEFI 2.7, device address = host address + Translation.
> +      // For GCD resource manipulation, we should use host address, so
> +      // Translation is subtracted from device address here.

(3) In general, the comment style requires comments like this:

  //
  // Add empty comment lines both before and after.
  //

>        Status = AddIoSpace (
> -                 RootBridges[Index].Io.Base,
> +                 RootBridges[Index].Io.Base - RootBridges[Index].Io.Translation,
>                   RootBridges[Index].Io.Limit - RootBridges[Index].Io.Base + 1
>                   );
>        ASSERT_EFI_ERROR (Status);

This looks fine.

> @@ -422,7 +449,7 @@ InitializePciHostBridge (
>                          EfiGcdIoTypeIo,
>                          0,
>                          RootBridges[Index].Io.Limit - RootBridges[Index].Io.Base + 1,
> -                        &RootBridges[Index].Io.Base,
> +                        &RootBridges[Index].Io.Base - RootBridges[Index].Io.Translation,
>                          gImageHandle,
>                          NULL
>                          );

(4) But this is wrong (operating under the assumption that
PCI_ROOT_BRIDGE_APERTURE providing device addresses). Namely, 5th
parameter of gDS->AllocateIoSpace() is an in/out parameter:

[MdeModulePkg/Core/Dxe/Gcd/Gcd.c]

EFI_STATUS
EFIAPI
CoreAllocateIoSpace (
  IN     EFI_GCD_ALLOCATE_TYPE  GcdAllocateType,
  IN     EFI_GCD_IO_TYPE        GcdIoType,
  IN     UINTN                  Alignment,
  IN     UINT64                 Length,
  IN OUT EFI_PHYSICAL_ADDRESS   *BaseAddress,
  IN     EFI_HANDLE             ImageHandle,
  IN     EFI_HANDLE             DeviceHandle OPTIONAL
  )

The patch, as written, takes the address of the Base field, and then
decreases that address by Translation * sizeof Base. The resultant
pointer is passed to the function as 5th argument.

I don't think that's what you meant :)

Instead, you have to translate the device address to host address first
(using a temporary variable), and pass that to the function. (Updating
the Base field back to the resultant / output value shouldn't be
necessary, because GcdAllocateType==EfiGcdAllocateAddress, so the
allocation is required to succeed at the exact address requested.)

> @@ -443,14 +470,18 @@ InitializePciHostBridge (
>
>      for (MemApertureIndex = 0; MemApertureIndex < ARRAY_SIZE (MemApertures); MemApertureIndex++) {
>        if (MemApertures[MemApertureIndex]->Base <= MemApertures[MemApertureIndex]->Limit) {
> +        // Base and Limit in PCI_ROOT_BRIDGE_APERTURE are device address.
> +        // According to UEFI 2.7, device address = host address + Translation.
> +        // For GCD resource manipulation, we should use host address, so
> +        // Translation is subtracted from device address here.
>          Status = AddMemoryMappedIoSpace (
> -                   MemApertures[MemApertureIndex]->Base,
> +                   MemApertures[MemApertureIndex]->Base - MemApertures[MemApertureIndex]->Translation,
>                     MemApertures[MemApertureIndex]->Limit - MemApertures[MemApertureIndex]->Base + 1,
>                     EFI_MEMORY_UC
>                     );
>          ASSERT_EFI_ERROR (Status);
>          Status = gDS->SetMemorySpaceAttributes (
> -                        MemApertures[MemApertureIndex]->Base,
> +                        MemApertures[MemApertureIndex]->Base - MemApertures[MemApertureIndex]->Translation,
>                          MemApertures[MemApertureIndex]->Limit - MemApertures[MemApertureIndex]->Base + 1,
>                          EFI_MEMORY_UC
>                          );
> @@ -463,7 +494,7 @@ InitializePciHostBridge (
>                            EfiGcdMemoryTypeMemoryMappedIo,
>                            0,
>                            MemApertures[MemApertureIndex]->Limit - MemApertures[MemApertureIndex]->Base + 1,
> -                          &MemApertures[MemApertureIndex]->Base,
> +                          &MemApertures[MemApertureIndex]->Base - MemApertures[MemApertureIndex]->Translation,
>                            gImageHandle,
>                            NULL
>                            );

(5) Same comment as (4) applies, to the 5th argument.

> @@ -824,12 +855,17 @@ NotifyPhase (
>
>            switch (Index) {
>            case TypeIo:
> +            // Base and Limit in PCI_ROOT_BRIDGE_APERTURE are device address.
> +            // According to UEFI 2.7, device address = host address + Translation.
> +            // For AllocateResource is manipulating GCD resource, we should use
> +            // host address here, so Translation is subtracted from Base and
> +            // Limit.
>              BaseAddress = AllocateResource (
>                              FALSE,
>                              RootBridge->ResAllocNode[Index].Length,
>                              MIN (15, BitsOfAlignment),
> -                            ALIGN_VALUE (RootBridge->Io.Base, Alignment + 1),
> -                            RootBridge->Io.Limit
> +                            ALIGN_VALUE (RootBridge->Io.Base, Alignment + 1) - RootBridge->Io.Translation,
> +                            RootBridge->Io.Limit - RootBridge->Io.Translation
>                              );
>              break;
>
> @@ -838,8 +874,8 @@ NotifyPhase (
>                              TRUE,
>                              RootBridge->ResAllocNode[Index].Length,
>                              MIN (63, BitsOfAlignment),
> -                            ALIGN_VALUE (RootBridge->MemAbove4G.Base, Alignment + 1),
> -                            RootBridge->MemAbove4G.Limit
> +                            ALIGN_VALUE (RootBridge->MemAbove4G.Base, Alignment + 1) - RootBridge->MemAbove4G.Translation,
> +                            RootBridge->MemAbove4G.Limit - RootBridge->MemAbove4G.Translation
>                              );
>              if (BaseAddress != MAX_UINT64) {
>                break;
> @@ -853,8 +889,8 @@ NotifyPhase (
>                              TRUE,
>                              RootBridge->ResAllocNode[Index].Length,
>                              MIN (31, BitsOfAlignment),
> -                            ALIGN_VALUE (RootBridge->Mem.Base, Alignment + 1),
> -                            RootBridge->Mem.Limit
> +                            ALIGN_VALUE (RootBridge->Mem.Base, Alignment + 1) - RootBridge->Mem.Translation,
> +                            RootBridge->Mem.Limit - RootBridge->Mem.Translation
>                              );
>              break;
>
> @@ -863,8 +899,8 @@ NotifyPhase (
>                              TRUE,
>                              RootBridge->ResAllocNode[Index].Length,
>                              MIN (63, BitsOfAlignment),
> -                            ALIGN_VALUE (RootBridge->PMemAbove4G.Base, Alignment + 1),
> -                            RootBridge->PMemAbove4G.Limit
> +                            ALIGN_VALUE (RootBridge->PMemAbove4G.Base, Alignment + 1) - RootBridge->PMemAbove4G.Translation,
> +                            RootBridge->PMemAbove4G.Limit - RootBridge->PMemAbove4G.Translation
>                              );
>              if (BaseAddress != MAX_UINT64) {
>                break;
> @@ -877,8 +913,8 @@ NotifyPhase (
>                              TRUE,
>                              RootBridge->ResAllocNode[Index].Length,
>                              MIN (31, BitsOfAlignment),
> -                            ALIGN_VALUE (RootBridge->PMem.Base, Alignment + 1),
> -                            RootBridge->PMem.Limit
> +                            ALIGN_VALUE (RootBridge->PMem.Base, Alignment + 1) - RootBridge->PMem.Translation,
> +                            RootBridge->PMem.Limit - RootBridge->PMem.Translation
>                              );
>              break;

(6) For all of these, I believe that we have to think about the corner
case when the Translation value is not a multiple of (Alignment + 1).

"Alignment" comes from the PCI BAR in question, whereas Base comes from
the platform PciHostBridgeLib. I think these are fairly independent (you
can plug a 3rd party, discrete PCI card into a board). I find it
plausible that the card has such a huge MMIO BAR (and alignment) that
the platform's Translation offset is not a multiple thereof.

So, which "view" has to be aligned here? The PCI (device) view, or the
host (CPU) view?

... Hmmm wait, the AllocateResource() function aligns BaseAddress
internally anyway. So, first, I don't understand why the pre-patch code
uses ALIGN_VALUE at the call site as well; second, due to the alignment
internal to AllocateResource(), we couldn't align *just* the PCI view
even if we wanted to.

So I guess this code is correct (due to the alignment internal to
AllocateResource()), but could we perhaps simplify it by passing

  RootBridge->Xxx.Base - RootBridge->Xxx.Translation

i.e., by dropping the outer alignment?

(To be clear, dropping the "outer" alignment, if it's a valid change,
should be done as a separate patch, before the translation is
introduced. I hope Ray can comment on this.)

>
> @@ -1152,6 +1188,7 @@ StartBusEnumeration (
>        Descriptor->AddrSpaceGranularity  = 0;
>        Descriptor->AddrRangeMin          = RootBridge->Bus.Base;
>        Descriptor->AddrRangeMax          = 0;
> +      // Ignore translation offset for bus
>        Descriptor->AddrTranslationOffset = 0;
>        Descriptor->AddrLen               = RootBridge->Bus.Limit - RootBridge->Bus.Base + 1;
>

(7) Ah, in this case, adding TypeBus under (2) is not necessary, just
ASSERT(FALSE) under the currently proposed "default" label.


> @@ -1421,7 +1458,12 @@ GetProposedResources (
>            Descriptor->Desc                  = ACPI_ADDRESS_SPACE_DESCRIPTOR;
>            Descriptor->Len                   = sizeof (EFI_ACPI_ADDRESS_SPACE_DESCRIPTOR) - 3;;
>            Descriptor->GenFlag               = 0;
> -          Descriptor->AddrRangeMin          = RootBridge->ResAllocNode[Index].Base;
> +          // AddrRangeMin in Resource Descriptor here should be device address
> +          // instead of host address, or else PCI bus driver cannot set correct
> +          // address into PCI BAR registers.
> +          // Base in ResAllocNode is a host address, so Translation is added.
> +          Descriptor->AddrRangeMin          = RootBridge->ResAllocNode[Index].Base +
> +              GetTranslationByResourceType (RootBridge, Index);
>            Descriptor->AddrRangeMax          = 0;
>            Descriptor->AddrTranslationOffset = (ResStatus == ResAllocated) ? EFI_RESOURCE_SATISFIED : PCI_RESOURCE_LESS;
>            Descriptor->AddrLen               = RootBridge->ResAllocNode[Index].Length;
> diff --git a/MdeModulePkg/Bus/Pci/PciHostBridgeDxe/PciHostResource.h b/MdeModulePkg/Bus/Pci/PciHostBridgeDxe/PciHostResource.h
> index 8612c0c..662c2dd 100644
> --- a/MdeModulePkg/Bus/Pci/PciHostBridgeDxe/PciHostResource.h
> +++ b/MdeModulePkg/Bus/Pci/PciHostBridgeDxe/PciHostResource.h
> @@ -38,6 +38,8 @@ typedef enum {
>
>  typedef struct {
>    PCI_RESOURCE_TYPE Type;
> +  // Base is a host address instead of a device address when address translation
> +  // exists and host address != device address
>    UINT64            Base;
>    UINT64            Length;
>    UINT64            Alignment;
> diff --git a/MdeModulePkg/Bus/Pci/PciHostBridgeDxe/PciRootBridgeIo.c b/MdeModulePkg/Bus/Pci/PciHostBridgeDxe/PciRootBridgeIo.c
> index dc06c16..04ed411 100644
> --- a/MdeModulePkg/Bus/Pci/PciHostBridgeDxe/PciRootBridgeIo.c
> +++ b/MdeModulePkg/Bus/Pci/PciHostBridgeDxe/PciRootBridgeIo.c
> @@ -86,12 +86,23 @@ CreateRootBridge (
>            (Bridge->AllocationAttributes & EFI_PCI_HOST_BRIDGE_COMBINE_MEM_PMEM) != 0 ? L"CombineMemPMem " : L"",
>            (Bridge->AllocationAttributes & EFI_PCI_HOST_BRIDGE_MEM64_DECODE) != 0 ? L"Mem64Decode" : L""
>            ));
> +  // We don't see any scenario for bus translation, so translation for bus is just ignored.
>    DEBUG ((EFI_D_INFO, "           Bus: %lx - %lx\n", Bridge->Bus.Base, Bridge->Bus.Limit));
> -  DEBUG ((EFI_D_INFO, "            Io: %lx - %lx\n", Bridge->Io.Base, Bridge->Io.Limit));
> -  DEBUG ((EFI_D_INFO, "           Mem: %lx - %lx\n", Bridge->Mem.Base, Bridge->Mem.Limit));
> -  DEBUG ((EFI_D_INFO, "    MemAbove4G: %lx - %lx\n", Bridge->MemAbove4G.Base, Bridge->MemAbove4G.Limit));
> -  DEBUG ((EFI_D_INFO, "          PMem: %lx - %lx\n", Bridge->PMem.Base, Bridge->PMem.Limit));
> -  DEBUG ((EFI_D_INFO, "   PMemAbove4G: %lx - %lx\n", Bridge->PMemAbove4G.Base, Bridge->PMemAbove4G.Limit));
> +  DEBUG ((DEBUG_INFO, "            Io: %lx - %lx translation=%lx\n",
> +          Bridge->Io.Base, Bridge->Io.Limit, Bridge->Io.Translation
> +          ));
> +  DEBUG ((DEBUG_INFO, "           Mem: %lx - %lx translation=%lx\n",
> +          Bridge->Mem.Base, Bridge->Mem.Limit, Bridge->Mem.Translation
> +          ));
> +  DEBUG ((DEBUG_INFO, "    MemAbove4G: %lx - %lx translation=%lx\n",
> +          Bridge->MemAbove4G.Base, Bridge->MemAbove4G.Limit, Bridge->MemAbove4G.Translation
> +          ));
> +  DEBUG ((DEBUG_INFO, "          PMem: %lx - %lx translation=%lx\n",
> +          Bridge->PMem.Base, Bridge->PMem.Limit, Bridge->PMem.Translation
> +          ));
> +  DEBUG ((DEBUG_INFO, "   PMemAbove4G: %lx - %lx translation=%lx\n",
> +          Bridge->PMemAbove4G.Base, Bridge->PMemAbove4G.Limit, Bridge->PMemAbove4G.Translation
> +          ));

(8) I suggest capitalizing "Translation" in the debug output.

(9) The indentation is not idiomatic, it should be

  DEBUG ((
    ...
    ...
    ));

>
>    //
>    // Make sure Mem and MemAbove4G apertures are valid
> @@ -206,7 +217,10 @@ CreateRootBridge (
>      }
>      RootBridge->ResAllocNode[Index].Type     = Index;
>      if (Bridge->ResourceAssigned && (Aperture->Limit >= Aperture->Base)) {
> -      RootBridge->ResAllocNode[Index].Base   = Aperture->Base;
> +      // Base in ResAllocNode is a host address, while Base in Aperture is a
> +      // device address, so translation needs to be subtracted.
> +      RootBridge->ResAllocNode[Index].Base   = Aperture->Base -
> +        Aperture->Translation;
>        RootBridge->ResAllocNode[Index].Length = Aperture->Limit - Aperture->Base + 1;
>        RootBridge->ResAllocNode[Index].Status = ResAllocated;
>      } else {
> @@ -403,6 +417,28 @@ RootBridgeIoCheckParameter (
>    return EFI_SUCCESS;
>  }
>
> +EFI_STATUS
> +RootBridgeIoGetMemTranslationByAddress (
> +  IN PCI_ROOT_BRIDGE_INSTANCE               *RootBridge,
> +  IN UINT64                                 Address,
> +  IN OUT UINT64                             *Translation
> +  )
> +{
> +  if (Address >= RootBridge->Mem.Base && Address <= RootBridge->Mem.Limit) {
> +    *Translation = RootBridge->Mem.Translation;
> +  } else if (Address >= RootBridge->PMem.Base && Address <= RootBridge->PMem.Limit) {
> +    *Translation = RootBridge->PMem.Translation;
> +  } else if (Address >= RootBridge->MemAbove4G.Base && Address <= RootBridge->MemAbove4G.Limit) {
> +    *Translation = RootBridge->MemAbove4G.Translation;
> +  } else if (Address >= RootBridge->PMemAbove4G.Base && Address <= RootBridge->PMemAbove4G.Limit) {
> +    *Translation = RootBridge->PMemAbove4G.Translation;
> +  } else {
> +    return EFI_INVALID_PARAMETER;
> +  }
> +
> +  return EFI_SUCCESS;
> +}
> +
>  /**
>    Polls an address in memory mapped I/O space until an exit condition is met,
>    or a timeout occurs.
> @@ -658,13 +694,24 @@ RootBridgeIoMemRead (
>    )
>  {
>    EFI_STATUS                             Status;
> +  PCI_ROOT_BRIDGE_INSTANCE               *RootBridge;
> +  UINT64                                 Translation;
>
>    Status = RootBridgeIoCheckParameter (This, MemOperation, Width, Address,
>                                         Count, Buffer);
>    if (EFI_ERROR (Status)) {
>      return Status;
>    }
> -  return mCpuIo->Mem.Read (mCpuIo, (EFI_CPU_IO_PROTOCOL_WIDTH) Width, Address, Count, Buffer);
> +
> +  RootBridge = ROOT_BRIDGE_FROM_THIS (This);
> +  Status = RootBridgeIoGetMemTranslationByAddress (RootBridge, Address, &Translation);
> +  if (EFI_ERROR (Status)) {
> +    return Status;
> +  }
> +
> +  // Address passed to CpuIo->Mem.Read should be a host address instead of
> +  // device address, so Translation should be subtracted.
> +  return mCpuIo->Mem.Read (mCpuIo, (EFI_CPU_IO_PROTOCOL_WIDTH) Width, Address - Translation, Count, Buffer);
>  }
>
>  /**
> @@ -705,13 +752,24 @@ RootBridgeIoMemWrite (
>    )
>  {
>    EFI_STATUS                             Status;
> +  PCI_ROOT_BRIDGE_INSTANCE               *RootBridge;
> +  UINT64                                 Translation;
>
>    Status = RootBridgeIoCheckParameter (This, MemOperation, Width, Address,
>                                         Count, Buffer);
>    if (EFI_ERROR (Status)) {
>      return Status;
>    }
> -  return mCpuIo->Mem.Write (mCpuIo, (EFI_CPU_IO_PROTOCOL_WIDTH) Width, Address, Count, Buffer);
> +
> +  RootBridge = ROOT_BRIDGE_FROM_THIS (This);
> +  Status = RootBridgeIoGetMemTranslationByAddress (RootBridge, Address, &Translation);
> +  if (EFI_ERROR (Status)) {
> +    return Status;
> +  }
> +
> +  // Address passed to CpuIo->Mem.Write should be a host address instead of
> +  // device address, so Translation should be subtracted.
> +  return mCpuIo->Mem.Write (mCpuIo, (EFI_CPU_IO_PROTOCOL_WIDTH) Width, Address - Translation, Count, Buffer);
>  }
>
>  /**
> @@ -746,6 +804,8 @@ RootBridgeIoIoRead (
>    )
>  {
>    EFI_STATUS                                    Status;
> +  PCI_ROOT_BRIDGE_INSTANCE                      *RootBridge;
> +
>    Status = RootBridgeIoCheckParameter (
>               This, IoOperation, Width,
>               Address, Count, Buffer
> @@ -753,7 +813,12 @@ RootBridgeIoIoRead (
>    if (EFI_ERROR (Status)) {
>      return Status;
>    }
> -  return mCpuIo->Io.Read (mCpuIo, (EFI_CPU_IO_PROTOCOL_WIDTH) Width, Address, Count, Buffer);
> +
> +  RootBridge = ROOT_BRIDGE_FROM_THIS (This);
> +
> +  // Address passed to CpuIo->Io.Read should be a host address instead of
> +  // device address, so Translation should be subtracted.
> +  return mCpuIo->Io.Read (mCpuIo, (EFI_CPU_IO_PROTOCOL_WIDTH) Width, Address - RootBridge->Io.Translation, Count, Buffer);
>  }
>
>  /**
> @@ -788,6 +853,8 @@ RootBridgeIoIoWrite (
>    )
>  {
>    EFI_STATUS                                    Status;
> +  PCI_ROOT_BRIDGE_INSTANCE                      *RootBridge;
> +
>    Status = RootBridgeIoCheckParameter (
>               This, IoOperation, Width,
>               Address, Count, Buffer
> @@ -795,7 +862,12 @@ RootBridgeIoIoWrite (
>    if (EFI_ERROR (Status)) {
>      return Status;
>    }
> -  return mCpuIo->Io.Write (mCpuIo, (EFI_CPU_IO_PROTOCOL_WIDTH) Width, Address, Count, Buffer);
> +
> +  RootBridge = ROOT_BRIDGE_FROM_THIS (This);
> +
> +  // Address passed to CpuIo->Io.Write should be a host address instead of
> +  // device address, so Translation should be subtracted.
> +  return mCpuIo->Io.Write (mCpuIo, (EFI_CPU_IO_PROTOCOL_WIDTH) Width, Address - RootBridge->Io.Translation, Count, Buffer);
>  }
>
>  /**
> @@ -1615,25 +1687,39 @@ RootBridgeIoConfiguration (
>
>      Descriptor->Desc = ACPI_ADDRESS_SPACE_DESCRIPTOR;
>      Descriptor->Len  = sizeof (EFI_ACPI_ADDRESS_SPACE_DESCRIPTOR) - 3;
> +    // According to UEFI 2.7, RootBridgeIo->Configuration should return address
> +    // range in CPU view (host address), and ResAllocNode->Base is already a CPU
> +    // view address (host address).
>      Descriptor->AddrRangeMin  = ResAllocNode->Base;
>      Descriptor->AddrRangeMax  = ResAllocNode->Base + ResAllocNode->Length - 1;
>      Descriptor->AddrLen       = ResAllocNode->Length;
>      switch (ResAllocNode->Type) {
>
>      case TypeIo:
> -      Descriptor->ResType       = ACPI_ADDRESS_SPACE_TYPE_IO;
> +      Descriptor->ResType               = ACPI_ADDRESS_SPACE_TYPE_IO;
> +      Descriptor->AddrTranslationOffset = RootBridge->Io.Translation;
>        break;
>
>      case TypePMem32:
> -      Descriptor->SpecificFlag = EFI_ACPI_MEMORY_RESOURCE_SPECIFIC_FLAG_CACHEABLE_PREFETCHABLE;
> +      Descriptor->SpecificFlag          = EFI_ACPI_MEMORY_RESOURCE_SPECIFIC_FLAG_CACHEABLE_PREFETCHABLE;
> +      Descriptor->AddrTranslationOffset = RootBridge->PMem.Translation;
> +      Descriptor->ResType               = ACPI_ADDRESS_SPACE_TYPE_MEM;
> +      Descriptor->AddrSpaceGranularity  = 32;
> +      break;
> +
>      case TypeMem32:
> +      Descriptor->AddrTranslationOffset = RootBridge->Mem.Translation;
>        Descriptor->ResType               = ACPI_ADDRESS_SPACE_TYPE_MEM;
>        Descriptor->AddrSpaceGranularity  = 32;
>        break;
>
>      case TypePMem64:
> -      Descriptor->SpecificFlag = EFI_ACPI_MEMORY_RESOURCE_SPECIFIC_FLAG_CACHEABLE_PREFETCHABLE;
> +      Descriptor->SpecificFlag          = EFI_ACPI_MEMORY_RESOURCE_SPECIFIC_FLAG_CACHEABLE_PREFETCHABLE;
> +      Descriptor->AddrTranslationOffset = RootBridge->PMemAbove4G.Translation;
> +      Descriptor->ResType               = ACPI_ADDRESS_SPACE_TYPE_MEM;
> +      Descriptor->AddrSpaceGranularity  = 64;
>      case TypeMem64:
> +      Descriptor->AddrTranslationOffset = RootBridge->MemAbove4G.Translation;
>        Descriptor->ResType               = ACPI_ADDRESS_SPACE_TYPE_MEM;
>        Descriptor->AddrSpaceGranularity  = 64;
>        break;
> diff --git a/MdeModulePkg/Include/Library/PciHostBridgeLib.h b/MdeModulePkg/Include/Library/PciHostBridgeLib.h
> index d42e9ec..21ee8cd 100644
> --- a/MdeModulePkg/Include/Library/PciHostBridgeLib.h
> +++ b/MdeModulePkg/Include/Library/PciHostBridgeLib.h
> @@ -20,8 +20,16 @@
>  // (Base > Limit) indicates an aperture is not available.
>  //
>  typedef struct {
> +  // Base and Limit are the device address instead of host address when
> +  // Translation is not zero
>    UINT64 Base;
>    UINT64 Limit;
> +  // According to UEFI 2.7, Device Address = Host Address + Translation,
> +  // so Translation = Device Address - Host Address.
> +  // On platforms where Translation is not zero, Translation is probably
> +  // negative for we may translate an above-4G host address into a below-4G
> +  // device address for legacy PCIe device compatibility.
> +  UINT64 Translation;
>  } PCI_ROOT_BRIDGE_APERTURE;
>
>  typedef struct {
>

(10) I suggest replacing the "negative" language with "the subtraction
is to be performed with UINT64 wrap-around semantics".


I've made some comments, but I admit my understanding is quite limited;
sorry about that.

Thanks
Laszlo